Removal of lead from columbium mineral concentrate

ABSTRACT

A process for removing lead from columbium bearing material, such as minerals and concentrates, which comprises heating the material to at least about 650*C with up to 50% by weight of an inorganic metal chloride, or ammonium chloride, alkaline earth metal chlorides being preferred.

Kentro et a1.

REMOVAL OF LEAD FROM COLUMBIUM MINERAL CONCENTRATE Inventors: Dan M. Kentro, New York, N.Y.;

James W. Cole, Boulder City, Nev.

Molybdenum Corporation of America, Louviers, Colo.

Filed: May is, 1972 Appl. No.: 254,406

Assignee:

References Cited UNITED STATES PATENTS 2/1936 Doom 75/84 X 3/1939 Leemans 75/84 X 8/1950 Gardner 75/84 Jan. 28, 1975 2,905,549 9/1959 Taylor et al. 75/84 2,909,426 10/1959 Rathmann et a1. 75/84 X 3,132,024 5/1964 Matricardi 75/84 3,141,766 7/1964 Burkin et al. 75/84 X 3,188,200 6/1965 Brothers 75/84 3,453,101 7/1969 Takahashi et al 75/2 Primary Examiner-Richard D. Lovering Assistant Examiner-R. E. Schafer Attorney, Agent, or Firm-Sheridan, Ross & Fields [5 7] ABSTRACT A process for removing lead from columbium bearing material, such as minerals and concentrates, which comprises heating the material to at least about 650C with up to 50% by weight of an inorganic metal chloride, or ammonium chloride, alkaline earth metal chlorides being preferred.

14 Claims, No Drawings REMOVAL OF LEAD FROM COLUMBIUM MINERAL CONCENTRATE BACKGROUND OF THE INVENTION The metal columbium is in demand for use as an alloying agent in carbon and alloy steels and in nonferrous metals, in advanced airframe systems, and for other specialized uses. A number of applications for the metal require a high purity product which is low in lead content. For example, the ASTM specifications for ferrocolumbium alloy limit its lead content to less than 0.01% by weight. (Percentage compositions referred to hereinafter are by weight.)

A major source for columbium is the mineral pyrochlore in which the metal is present largely as columbate along with other metals in combined form, such as, barium, calcium, iron, lead, rare earths, sodium, thorium, tin, titanium and others.

The average lead content of pyrochlore mineral concentrate is about 0.3 1% and the columbium content is about 60% based on Cb O The major percentage of all of these metal impurities can be separated from columbium in pyrochlore and other columbiumcontaining minerals by conventional beneficiation procedures, with the exception of lead. For example, a commercial columbium concentrate from pyrochlore contains about 58-60% of columbium as Cb O and from 0.2-1% of lead. a

A ferrocolumbium alloy produced from a concentrate containing this much lead has a lead content from about 0.050.2%, far above the ASTM tolerance of 0.01%. If a concentrate could be produced having a lead content of 0.05% or less, ferrocolumbium alloy could be produced from it with a lead content meeting the ASTM specifications. Prior to this invention a columbium concentrate could not be produced having a lead content less than about 0.2 1%.

Accordingly, it is an object of this invention to provide a process for removing lead from columbium bearing material.

It is another object of this invention to provide a process for separating lead from columbium when they are present together in mixtures.

STATEMENT OF THE INVENTION A process for the removal of lead from columbium bearing material which comprises mixing columbium concentrate with up to 50% of an inorganic metal chloride or ammonium chloride, heating the mixture above about 650C for a period sufficient to eliminate substantially all of the lead as lead compounds or otherwise.

DETAILED DESCRIPTION OF THE INVENTION 650C for a period of up to 2 hours for removal of lead. The treated concentrate is leached with water or dilute hydrochloric acid as necessary to remove excess inorganic metal chloride after which ferrocolumbium alloy is produced from the treated concentrate by conventional processes.

The particle size of the concentrate is not critical, the only requirement being that it be sufficiently small to provide uniform mixing with the chloride. The process is applicable to minerals, ores, and other materials in which columbium is present with lead.

The concentrate used is normally a commercial grade concentrate produced by standard beneficiation techniques including a final froth flotation step.

The preferred inorganic metal chlorides are the alkaline earth metal chlorides, particularly, the chlorides of calcium and magnesium. Other chlorides found to be satisfactory are those of ammonium, the alkali metals, rare earth metals, and iron. Obviously, mixtures of these chlorides are operative. While the explanation for the surprising effect of almost complete removal of lead is not known, it appears that the presence of chlorine in the form of an inorganic metal chloride plays a significant role in removal of the lead through volatilization of lead or lead compounds. Inorganic metal chlorides in general are operative. The chloride may be formed in situ by adding reactants which react to form the chloride. For example, lime and hydrochloric acid may be added in amounts to produce the required amount of calcium chloride.

The inorganic metal chloride may be used in amounts up to 50% by weight of the mixture. The amount used will depend on various factors including the lead content and physical condition of the concentrate, chloride used, as well as economic factors. Amounts up to 50% have been used with success. The preferred amount is between about 20-50%.

The lower limit of the temperature range within which the concentrate is heated is critical and is about 650C. It must be high enough to volatilize the lead or lead compounds present under the reaction conditions.

The upper limitisnot critical and is dependent upon economic feasibility considerations as respects process time, heat utilization, purity of the: product, and others. A preferred range is between 7001000C.

The time for heating the concentrate will vary depending on a number of factors such as the lead con tent of the concentrate, the chloride used, the physical condition of the concentrate, and the desired purity of the product. Times between about 15-l20 minutes are preferred.

The test results reported in the following tables were obtained from tests made in accordance with the above-described procedure. They were selected as illustrative but not limiting of the invention. The concentrate used in the examples contained 61.35% columbium as Cb O and 0.33% lead. Fifty gram samples of concentrate were used. The percent lead removed was calculated by analysis of the sample before and after treatment. For each test the time of roast, temperature at which the roast was performed, weight percent of chloride additive based on weight of the concentrate sample, and weight percent of lead eliminated are given under appropriate headings.

The test results of Table l are for tests selected to illustrate the operativeness of the process with various inorganic metal chlorides under varying reaction conditions.

TABLE 1 Test Wt. Roast Time Wt. 70 Pb No. Chloride Chloride Temperature (Min.) Eliminated l IOOOC 3O 2 CaCl 50 lOO0C 90 100 3 CaCl; 50 l000C 90 100 4 MgCl .6 H 0 50 l000C 60 60 5 MgCl .6 H O l00 l000C I20 95 6 BaCl- 50 l000C 30 45 7 NaCl 50 l 000C 90 50 8 KCl 50 l000C 60 60 9 NH Cl 50 l000C 120 80 10 FeCl 50 l 000C 60 50 l l Rare Earth l0 l000C )0 Chloride Mixture Table l test results demonstrate operativeness of the 7 From the above test results it is apparent that use of 7 process with a wide range of inorganic metal chlorides under variable reaction conditions thus demonstrating the equivalency of the inorganic metal chlorides. From 45l00% lead was eliminated using alkaline earth metal chlorides and 50% and above lead elimination was obtained with the other metal chlorides.

The tests for which results are presented in Table 2 were selected to demonstrate the operativeness of the process when the chloride additive is formed in situ.

Test results are presented in Table 5 below from tests conducted to examine the effect of varying the process temperature while maintaining the amount of chloride additive and roast time constant.

TABLE 2 Test Amount of Roast Time Wt. Ph

No. Reactants Reactants Temperature (Min.) Eliminated 1 HC] cc l000C 90 85 CaO l0 gms. 2 NaCl 1000C 90 70 CaO 15% The results of Table 2 illustrate that the process operates with up to 85% elimination of lead when the chloride additive is formed in situ through the addition of reactants which react to form the chloride.

The results shown in Table 3 are for tests conducted to demonstrate the effect of varying the amounts of the chloride additive while maintaining the temperature and roast time constant.

TABLE 3 Test Wt. Roast Time Wt. Pb No. Chloride Chloride Temp. (Min.) Eliminated 1 CaCl, 5 1000C 90 45 2 do. 10 do. do. 70

3 do. 20 do. do. 75

4 do, 30 do. do. 100

5 do. do. do. 100

6 do. 10 700C do. 30

7 do. 20 do. do. 50

8 do. 30 do. do. 50

9 do. 40 do. do. 50

The results of Table 3 show that for a typical inorganic metal chloride, amounts from 5-40% can be used within the operable temperature and roast time ranges with -100% lead elimination.

The results of Table 4 below are for tests made to investigate the effect of varying the roast time while TABLE 5 Test Wt.% Roast Timc Wt. Pb

No. Chloride Chloride Temp. (Min.) Eliminated 1 CaCl, 30 950C 90 I00 2 do. do. 900C do. 88

3 do. do. 850C do. 94

4 do. do. 800C do. 77

5 do. do. 750C do. 63

6 do. do. 700C do.

From the results of Table 5 it can be observed that for a typical chloride additive the operable temperature range is above about 700C for 50% elimination of lead and above with 100% elimination obtained as the tem- 50 perature approaches the preferred upper limit of The invention provides an economically feasible process for the elimination of lead from columbium concentrates. Concentrates are produced from which ferrocolumbium alloys can be made containing less than 0.01% lead, well within the ASTM specifications. The process can be economically used to separate lead from columbium in other applications in which such an effective separation may not be required, such as rough keeping the temperature and amount of chloride addiseparation in unconcentrated ores and minerals, and

tive constant.

other materials.

TABLE 4 Test No. Wt. Chloride Temperature Roast Time (Min.) Wt. Pb Eliminated l 30 l000C 3O 2 do. do. 45

3 do. do. 60

4 do. do. 75 I00 5 do. do. 90 I00 6 5% NH Cl do. 70

10% CaCl What is claimed is:

1. A process for removing lead from columbium mineral concentrates which comprises:

a. adding to the columbium mineral concentrates an inorganic chloride selected from the group consisting of alkaline earth metal chlorides, alkali metal chlorides, iron chlorides, rare earth metal chlorides, and amonium chloride, and

b. heating the mixture of (a) at a temperature of at least 650C for a period sufficient to remove substantially all of the lead from the columbium bearing mineral concentrates.

2. The process of claim 1 in which the amount of inorganic chloride added is up to about 50% by weight of the mixture.

3. The process of claim 2 in which the mixture is heated for a period of at least fifteen minutes.

4. The process of claim 1 in which the inorganic chloride is calcium chloride.

5. The process of claim 1 in which the inorganic chlorideis magnesium chloride.

6. The processofclaim 1 in which the inorganic chlo-" ride is ammonium chloride. I

7. The process of claim 1 in which the inorganic chloride is barium chloride.

8. The process of claim 1 in which the inorganic chloride is potassium chloride.

9. The process of claim 1 in which the inorganic metal chloride is iron chloride.

10. The process of claim 1 in which the inorganic metal chloride is a rare earth metal chloride.

11. A process for removing lead from columbium mineral concentrates which comprises:

a. mixing with the columbium mineral concentrates in a finely divided state a finely divided solid inorganic chloride selected from the group consisting of alkaline earth metal chlorides, alkali metal chlorides, iron chlorides, rare earth metal chlorides, and amonium chloride, and mixtures thereof, in an amount up to about 50 percent by weight of the mixture, and

b. heating the mixture at a temperature above about 650C for a period of at least 15 minutes.

12. The process of claim 11 in which the mixture is heated from about 700C-1000C for a period from about 30l20 minutes.

13. The process ofclaim 12 in which excess inorganic metal salts are washed from the treated mixture.

14. The process of claim 11 in which the inorganic chloride is formed in situ by adding reactants which react under the reaction conditions to form the inorganic chloride. 

2. The process of claim 1 in which the amount of inorganic chloride added is up to about 50% by weight of the mixture.
 3. The process of claim 2 in which the mixture is heated for a period of at least fifteen minutes.
 4. The process of claim 1 in which the inorganic chloride is calcium chloride.
 5. The process of claim 1 in which the inorganic chloride is magnesium chloride.
 6. The process of claim 1 in which the inorganic chloride is ammonium chloride.
 7. The process of claim 1 in which the inorganic chloride is barium chloride.
 8. The process of claim 1 in which the inorganic chloride is potassium chloride.
 9. The process of claim 1 in which the inorganic metal chloride is iron chloride.
 10. The process of claim 1 in which the inorganic metal chloride is a rare earth metal chloride.
 11. A PROCESS FOR REMOVING LEAD FROM COLUMBIUM MENERAL CONCENTRATES WHICH COMPRISES: A. MIXING WITH THE COLUMBIAN MINERAL CONCENTRATES IN A FINELY DIVIDED STATE A FINELY DIVIDED SOLID INORGANIC CHLORIDE SELECTED FROM THE GROUP CONSISTING OF ALKALINE EARTH METAL CHLORIDES, ALKALI METAL CHLORIDES, IRON CHLORIDES, RARE EARTH METAL CHLORIDES, AND AMONIUM CHLORIDE, AND MIXTURES THEREOF, IN AM AMOUNT UP TO ABOUT 50 PERCENT BY WEIGHT OF THE MIXTURE, AND B. HEATING THE MIXTURE AT A TEMPERATURE ABOVE ABOUT 650*C FOR A PERIOD OF AT LEAST 15 MINUTES.
 12. The process of claim 11 in which the mixture is heated from about 700*C-1000*C for a period from about 30-120 minutes.
 13. The process of claim 12 in which excess inorganic metal salts are washed from the treated mixture.
 14. The process of claim 11 in which the inorganic chloride is formed in situ by adding reactants which react under the reaction conditions to form the inorganic chloride. 